An electrowetting display is an image display system where multiple pixels each filled with two phases of an aqueous medium and an oily color ink are arranged on a substrate, and the interface affinity of aqueous medium/oily color ink is controlled for each pixel by on-off voltage application to those pixels to thereby develop/aggregate the oily color ink on the substrate for image display (NPL 1). The colorant for use in electrowetting displays is required to have a high solubility in low-polar solvents and a high molar absorbance coefficient (PTL 1, PTL 2).
PTL 3 describes use of monoazo compounds similar to those of the present invention as dyes for polyester fibers.